Press leveling means



Feb. 29, 1944. BENH I 2,343,167

PRESS LEVELING MEANS Filed June 21, 1941 1 4 Sheets-Sheet 2 III 'IIIIIIIIIII Attomzgs- Feb. 29, 1944. 0.5. BENCH v PRESS LEVELINQMEANS Filed June 21, 1941 4 Sheet s-Sheet 4 O O O l 5 A 4 n 6 lb J 3 m w I r m 9 I m u l O O O O O 0 ITEM lhventor DAVl t. BENCH Patented a. 29, on

UNITED ST TES PATENT orrlcs- 2,343,101 ranss rnvsrmc MEANS Davfl 1:. Bench, Dayton, Ohio, assignor to The Hydraulic Development Corporation, Inc., Wilmington, Del, a corporation of Delaware Application June 21, 1941, Serial No. 399,168

11 Claims.

This invention relates to control means and, more particularly, to means responsive to deviations of a movable member from its normal plane while said member is in motion..

It is an object of this invention to provide a device which comprises a reference member arranged to move parallel to its starting position and, together with an element, to be controlled, which element is adapted to vary its angle relative to said reference member.

It is anotherobiect of the invention to provide a device having a reference member which is adapted to rest on a more or less tiltable element and to move in unison therewith, saldreference member being arranged so as to move substantially parallel to its starting plane irrespective of the tilting movement of said tiltable element.

Another object of the invention consists in the provision of a device comprising a reference element guided in stationary means so as to remain parallel to its starting position and resting on and moving together with a member to be controlled, which member, when in motion, may vary its plane with regard to its starting plane.

It is a further object of the invention to provide a press in which the press platen has in constant engagement therewith an element movable in unison with said platen and guided in a stationary portion of the press so as, during its motion, to remain substantially parallel to its starting position, thereby serving as a reference element with regard to which any tilting or bending movement of said platen during the movement of the latter may be measured and corrected.

Still another object of the invention consists in the provision of a press as described in the preceding paragraph. which comprises means for translating the tilting or bending movement of the platen with regard to the reference member to a magnifying device.

It is a further object to provide a press comprising a press head and a press platen reciprocable by spaced hydraulically operable plungers. in which the press head has mounted therein a reciprocable element resting on the platen and guided in the press head so as to move substantially parallel to its initial position irrespective ofthe deflection or bending movement of the platen, and to cause a restriction of the supply a press having a reciprocable element resting on a press platen but moving parallel to its initial position irrespective of bending or tilting movements of-the platen and adapted, in response to bending or-tilting movements of the platen, to

initiate the operation of electric means for correcting said bending or tilting movements.

It is another object to provide a press which has a platen reciprocable by a plurality "of spaced fluid operable piungers and supporting a reference member which is reciprocabie so as to move parallel to its initial position irrespective of deflections or bending movements of the platen,

Y while the platen is provided with means respon- Figure 3 is a modification of the arrangement shown in Figure 2. I

Figure 4 is a section along the line 4-4 of Fig.- ure 1. Figure 5 is a similar sectionthrough a modified arrangement of the invention.

Figures 6, 'l and 8 show a correctingmovement of the device according to the invention. Figure 9 shows a hydraulic press similar to that of Figure 1, with six press cylinder-pistonassemblies connected to a long platen.

Figures 10 and 11 show further modifications of the invention.

General arrangement The device according to the invention comprises a reciprocable reference member movable in stationary guiding means so as to maintain the reference member continuously parallel to its of driving fluid to said plungers in accordance with tilting or bending forces deflecting the platen from its normal plane.

It is also an object of the invention to provide initial position. The reference member rests upon a tiltable element, the tilting or bending movements of which are to be controlled.

Inasmuch as the reference member always maintains-a position parallel to its initial position, any bending or tilting movement of the tiltable element respectively dccreases and increases the space between a certain portion of the platen and the adjacent portion of the reference memher. This decrease or increase, when reaching a predetermined value, actuates an electric switch .which in its turn shifts a flow-control member "adapted to impose upon an element of the switch a movement larger than the change in distance between two predetermined points on said reference member andsaid platen respectively in'response to which change the said mechanism operates.

' Structural arrangement Referring first to Figure 1, the press shown therein merely comprises those parts which are necessary for a proper understanding of the invention.

In Figure 1 the press head I comprises two cylinders II and I2 having reciprocably mounted therein plungers l3 and I4 respectively, connected with the press platen 15. Each cylinder H, I2 is provided with a surge valve l5, l1, extending into the fluid reservoir or surge tank l8 and adapted, when open, to admit fluid from the tank into the cylinders II and I2, or vice.

versa.

The surge valves l and I1 serve primarily to prefill the cylinders II and I2 at the first portion of the pressing stroke when the plungers I3 and I4 move downwardly. The surge valve I5 communicates with a pilot conduit l8 which leads to a conduit connected to the lower portion of the cylinders II and I2 and communicating with a pilot line 2 I leading to the surge valve". Also connected to the conduit 25 are a pressure relief valve 22 and a check valve 23.

Branching oil from the conduit 25 is a conduit 24 leading to a main cylinder release and pump by-pass valve 25, which communicates through conduit 25 with a conduit 21 leading to th upper portion of the press cylinder l I. The main cylinder release and pump by-pass valve 25 is provided for releasing the Pressure in, the upper portion of the press cylinder [I at. the initiation of the retraction stroke of the press platen. The surge valve l5 and the valve 25 do not form a part of the present invention and tuna more detailed description thereof reference may respectively be had to U. 5. Patent 2,193,248 and U. S. Patent 2,268,205.

- The conduit. 21 leads to a two-way valve 28 which is connected by conduit 18 to one side of a reversible variable delivery pump 35, the other side of'which is connected by conduit 3| to the conduit 25.

Reciprocably mounted in the two-way valve 28 is a valve member 32- with two spaced pistons 33 and 34, which in their left hand position establish communication between the conduits 21 and 25 while, when the valve member 32 moves toward the right, the piston 33 is adapted to restrict or even to interrupt the flow of fluid between the conduits 29 and 21. The extent to which the valve member 32 may be moved toward the right is variable by an abutment screw 35 adapted to engage the piston 34. The valve'member 32 is connected with an armature 35, the movement or which is controlled by the solenoid 31. Also connected with the armature 35 is a spring 38 5 continuously urging the armature and, thereby,

also the valve member 32 toward the left.

The valve 28 controls the flow of fluid from the pump 33 to the cylinder- Similarly, a valve 39 is provided for controllin'gthe flow Qffluid from the pump 30 through conduits 40 and 4! to the cylinder l2. Inasmuch as all the parts pertain- 3 ing to the valve 38 correspond to those pertaining to the valve 28, the elements pertaining to the valve 39 have been provided with the same reference numerals as those of the valve 28, how ever, with the additional letter a.

The solenoids 31 and 31a are adapted electrically to communicate by lines 42, 43 and 44, 45, respectively, with the main supply lines 45 and 41. 20 The pump 35 is provided with a servomotor 48 having reciprocably mounted therein ajcontrol member 48 for varying the delivery of fluid of the pump. The servomotor 48 of the pump 35 cooperates with a pilot pump (not shown) 25 and comprises a spring which is adapted to shift the pump from full delivery forward stroke position to full delivery retraction stroke position. The pump 35 does not form a part of the present invention and for a more detailed 30 description thereof reference may be had to U. S.

Patent No. 2,184,665 to Emst.

The control member 48 isv connected by a lever system with the arm 5| of a three-arm lever 52, having one arm thereof pivotally connected as with an armature 53 pertaining to a solenoid 54 adaptedto be energized by clos ure of the starter switch blade 55, thereby electrically connecting the solenoid 54 with the main supply lines 45 and". v 40 The third arm 550i the three-arm lever 52 is adapted to be engaged by the collar 51 adjustably mounted on the ush rod 58 which car- I ries an adjustable stop ollar 59 and a further collar 55 adapted to be engaged by the platen army. 5

Arranged in the center of'the press head It is a reference member generally designated 52 and comprising a shaft 53 reciprocably mounted in-bushings 54 and 55 and rigidly connected to a beam 55 resting, by means of a ball 51, on the platen l5. Normally, the weight of the reference member '52 is sufficient to maintain the reference member continuously in contact with the platen l5. "However, if desired, springs 58 may be arranged for maintaining the reference member in constant contact with the platen IS. The beam 55' carries, at its ends, electric switches 59, 13, of which 'tl'ie switch 59 communicates through line 1| with the main supply 60 line 12 with the main supply line 45. The switch member 13 pertaining to the switch 58 is adapted to be actuated by spring 14 carried by an arm '15. The arm 15 in: its turn is supported by a bracket 15 which is adjustable onthe screw 11 and held in its desired place by nuts 18- and 13.

The screw 11 is carried by the platen IS. The switch 10, similarly, cooperates with a switch member 80 and a spring 8| supported by the arm 82, which is carried by the platen l5. In this way it is possible at all times of operation to eliminate any play, thereby maintaining the desired precision of the device according to the invention. It should be noted that normally spring14 does not deflectduring the operation line 41, while the switch 18 communicates through of the device but, in case of emergency, acts as ,a yielding member, thereby preventing destrucof an inch, and are preferably of the type known under the trade name of Micro-switch."

' Operation conduit 29, the valve and conduit 21 into the upper portion of the cylinder ll. Similarly, fluid from the pump ll passes through conduit ll, valve 39 and conduit 4i into the upper portion of the cylinder II. On the other hand, fluid is withdrawn through conduits 20 and ii from the lower portion of the cylinders II and [2.

While the rams l3 and i4 and, thereby, the platen I! move downwardly by gravity as fastas fluid is withdrawn from the lower portion of the cylinders II and ii, the fluid delivered by the pump iii into the cylinders ii and i2 is supplemented by fluid from the tank I! passing re the ram II, the platen it tends to return to its level position, as shown in Figure 8.

When the platen I! has reached its level position, the arm I! has receded'with regard to the switch member 13 so as to allow a spring (not shown) of the switch to open the latter again.

This breaks the energizing circuit for the solenoid 31 so that the spring II returns the valve member 32 to its Figure 1 position, thereby establishing the previous full connection between the pump II and the conduit 21. If, during the pressing stroke, the ram ll tends to run ahead of the ram II, the switch It will be closed in the manner described above, thereby energizing the solenoid 31a and reducing the fluid connection between the conduits II and 4! until the platen It has resumed its level position.

As will be clear from the above, the adjustment of the abutment screws and 3511' allows any desired variation of the fluid connections between the pump 3| and the cylinders ii and [2 respectively when one platen end runs ahead of the other platen end, thereby controlling the correcting or leveling operation and time required therefor. vThe springs 14 and 8| are so adjusted that, in level'position of the platen, they just engage the corresponding members/I3 and Ill. --1'he adjustable arrangement of the arms II-and 82 and springs I4 "and ll also makes it possible to spectively through the now open surge valves Iii and i1.

As soon as the platen i5 engages the work piece to be shaped, pressure starts to build up in the cylinders ii and II, with the result that the surge valves i6 and i1 close. While the platen l5 moves downwardly, the reference member 62 follows the platen i5 and is held in constant contact therewith.

Supposing that, during the actual pressing stroke which starts as soon as the platen I! engages the work piece, the resistance encountake up any .play between the respective spring and switch members. When the press'platen I! has reached theend of its pressing stroke, the energizing circuit for the solenoid SI isinterrupted by any convenient means well known to anyone skilled in the art,

so that the spring in the servomoter 48 shifts the pump 3| to full delivery retraction position.

Fluid now flows through conduits 3| and 20 into the lower portions of the cylinders ii and tered by the left end of the platen l5 and, thereby, of the ram I3 is less than the resistance encountered by the right end of the platen Ii and, thereby, of the ram it, it will be obvious that 'the left end of the platen i5 tends to run ahead of the right end of the platen ii. In other words,

. the platen I! has deviated from its normal plane shown in Figure 6 to that shown in Figure 7.

As a result thereof and due to the fact that the beam 66' of the referencemember 62 remains parallel to its starting position, the distance between the left end of the beam 66 and the arm I! supporting the spring ll decreases, thereby.

depressing the switch member I3 and closing the switch 9.

Current now flows from the main supply line I? through line "H, switch 89, line 42, solenoid 31 and line 43 back to the main supply'line 48. This causes energization of the solenoid 31 so that the armature it and the valve member '32 connected thereto are moved against the thrust of the spring 88 toward the right until the piston 34 engages the abutment member 35;

Depending on the adjustment of the abutment member 35, the flow of fluid from the pump 30 to the cylinder II will be more or less restricted, thereby reducing the pressure exerted on the ram II and also on the left end of the platen ii. In other words, since the fluid pressure exerted on the ram I4 is nowhigher than that exerted on l2, whereas fluid is withdrawn 'fom the upper portions of the cylinders II and I2 through conduits 21 and ll respectively. Pressure fluid also passes from the conduit ll through pilot lines I! and 2i, thereby opening the surge valves l6 and I1 and enabling fluid expelled from the cylinders II and, I! in excess of the fluid required by the pump II to return to the tank It.

-When the platen approaches the end of its retraction stroke, the platen arm Bl by engagement with the collar j, lifts the push rod 58 to such an extent that the collar 51 shift's'the arm 58 in anti-clockwise direction, thereby moving the pump 30 by means of the linkage 50 into substantially neutral or no delivery position. The press then comes to a halt and is ready for a new cycle.

Modifications I While, according to the embodiment of vFigures l and 2, the amount of movement of the switch members 13 and II during their engagement equals the amount of deflection of the corresponding platen portions from their leveling positions, the arrangement of Figure 3 is adapted to translate the amount of deflection of the platen into a greater movement of the switch members 13 and ti, thereby still further increasing the precision or sensitiveness of the device according to the invention. l v

According to the arrangement of Figure 3, the platen I5 is connected with a support 83 for pivotally connecting thereto one end of the arm 84, the other end of which is connected by a tension spring "to an arm 86 rigidly connected to the support 83. In this way, the arm 84 is constantly urged toward the arm 34. The space between the arm 84 and the arm 34' is controlled,

by an adjustable screw 91.

Pivotally connected to the arm 84 is an arm Q 88 carrying a spring 89 for engagement with ally connected to the beam 89. It will now'be obvious that when the distance between the leftie'nd of the beam 66 and the adjacent platen portion increases, the pivot 9| will be moved toward the right with regard to Figure 3, and moved through a distance greater than the increase in distance between the left end of the beam 66 and its adjacent platen portion, so that the switch 13 of the Figure 3 arrangement will either be actuated at a smaller deviation or the platen I from its level position than is the case with the switch I3 01 the Figures 1 and 2 arrangement, or the switch member :13 in Figure 3 will carry outa larger stroke than the switch member I3 in Figures 1 and 2. While Figure 3 illustrates a translating device for the switch I3, 69, it is, of course, un derstood that a corresponding arrangement is provided for the switch III, 89.

'Although the reference member 62 so far has been described as having only one beam 56, it is, of course, understood that the reference member may have a plurality of beams, for instance, two beams 92 and 93, as shown in Figure 5. In this particularinstance the beam 92 with its switches 94, 95 controls the proper movement of the rams 96 and 91, whereas the beam 93 with it's switches -93 and 99 controls the proper movement of the ramsIIlII and IIIL' In case va very long platen, or shear is provided, .the platen or shear may be actuated by a pininder may have associated therewith a, valve I93, I99, III), III, H2 and 3, similar in construction to the valves 28 and 39 of Figure 1, and controlled by a solenoid m, Ham, II'I, IIO-and nection with the press of Figure 1. However, it

will be understood that when-theplaten or sheet I 29 of Figure 9 deviates from itslevel position to a certain extent so that one end of the platen .rality of cylinders I02, I93, I04, I99, I95 and IE1, as shown in Figure 9. In this instance each cyl- The arrangement of is also adapted to correct any -lo l deflection onbul'ging out o! l the platen, arid also simultaneo aiflectionson each end of the'platen in the same direction, since the flow of fluid to respective cylinders will automatically be decreased, while the remaining cylinder-pistonsassemblies continue their normal pressing action. I

It will be appreciated that the shaft 63 oi the reference member 62 need by no means be in a perfect vertical position, and that a slight deviation oi the vertical position of the shaft 63 will not affect the proper functioning of the reference member 62, since the only thing that mattersis that the reference member moves in such a manner that it remains parallel to its start-' ing position. For this reason it is also by no means necessarythat the angle between the beam 69 or the beams 92 and 93 and the shaft 63 at a right angle, nor is it necessary that the beam 99 or the beams 92 and 93'are parallel to the platen I5.

It is also understood that the reference member 62 is not limited to the particular shape shown in Figures 1, 4 and 5, but may be replaced, for instance, by a pluralit of rods I21; I29 (Figure 10) restingon the platen I5, preferably the end portions thereof. Also in this instance, the reference rods I21, I28 are properly guided in stationary guiding means I29, I30 and I3I, I32.

According to the structure 'Figure 10, the springs I4 and 8| are-replaced by adjustable abut-- ment members I33 and I34 carried by the reference rods I21, I28 respectively and cooperating with the switches I35 and I 36. Otherwise, the operation is the same asthat described above in connection with Figure 1.

According to a further modification (Figure 11), the reference member 62 consists of a beams I31 guided on stationary guiding members I33 and I39 which, if desired, may be the same guiding members used for guiding the platen I44. The beam I3! is preferably provided with gibs I48 and adjusting screws I41 for assuring a proper guiding of the beam I31. The gib and screw arrangement I46, I41 may be of the type described in U. S. patent application No. 332,178,

' filed by PauLE. Flowers.

goes up while the other end goes down and the platen as a whole does not bulge out anywhere,v

only one valve, for instance, the valve III will be .moved into its flow-restricting position. If

this valve movement does not return the shear or platen I28 to its level position, due to particular circumstances which further increase the deviation of the platen or shear I23 from its normal level position, the next valve, in this instance the valve I99, will be moved to its flowrestricting position to cause the ram pertaining to the cylinder I03 to slow down its movement.

Ii, in spite of the actuation of the valve I33, due to particular circumstances, the platen or shear I28 should still increase its deviations, the valve H3 will come into action for supporting the valves I93 and I" in their leveling operation.

The beam I31 carries, adjacent its ends, the switches I40 and I4I, corresponding ,tothe switches 69 and III of Figure 1. These switches cooperate with actuating members I42 and I43 carriedby the platen I on whichthe beam I 31 rests by means of a ball I45. Also in this instance the operation of the reference member, in connection with the press, is the same as described with regard to Figure 1.

It is, oi course, understood that while the refer come, within the tion has been described in cooperation with electric means, the employment of the reference member is by no means limited to such an arrangement, but it is also possible to use the reference member in connection with mechanical or hydraulic control means instead'of the said electric means.

It will be understood that I desire tocomprehend within my invention such modifications as scope of the claims and the invention.

Having thus iully described my invention, what I claim'as new and desire to "secure by Letters Patent, is: v g

1. In combination'in a press, a reciprocable press platen, spaced hydraulic motor means for ing actuation of said valve means to restrict the reciprocating said platen, a reciprocable reference member separate from said motor means and resting on said platen so as to be movable in unison therewith, stationary guiding means for maintaining said'reference member parallel to its starting position when moving with said platen, first contact means provided adjacent two opposite ends of. said platen, second contact means supported by said reference member opposite said first contact means and adapted to engage the latter in response to tilting or bending movements of said platen, a fluid source for supplying pressure fluid to said motor means, and means responsive to the engagement of said contact means for controlling the supply of fluid to said hydraulic motor means. v

2. In combination in a press, a. press head comprising a plurality of spaced fluid operable cylinder-piston-assemblies, a press platen movably connected with said cylinder-piston-assemblies, a fluid source for supplying pressure fluid to said cylinder-piston-assemblies, valve means for controlling the supply of fluid from said fluid source to said cylinder-piston-assemblies, a reference member resting on said platen and movable in unison therewith, guiding means for guiding said reference member and maintaining the same in a position parallel to its starting position when said reference member moves with said platen, and controlling means associated with said platen and said reference member and responsive to tilting or bending movements of said platen for initiating actuation of said valve means to vary the supply of pressure fluid to said cylinder-pistonassemblies. 7

3. In combination in a press, a press head comprising a plurality of spaced fluid operable cylinder-piston-assemblies, a press platen movably connected with said cylinder-piston assemblies, a fluid source for supplying pressure fluid to said cylinder-piston-assemblies. valve means for controlling the supply of fluid from said fluid source to said cylinder-piston-assemblies, electric means operable to control the movement of said valve means, a reference member resting on said platen and movable in unison therewith, guiding means for guiding said reference member and maintaining the same in a position parallel to its starting position when said reference member moves with said platen, and contact means arranged on spaced opposite portions of said platen and adapted in response to tilting or bending movements of said platen to engage contact members on said reference member for energizing said electric means to move said valve means into a flow restrictin position for restricting the supply of fluid of the cylinder-piston-assembly adjacent the respective actuating contact means and contact members.

4. In combination in a press, a press head comder-piston-assemblies, a press platen movably connected .with said cylinder-piston-assemblies, a fluid source for supplying pressure fluid to said cylinder-piston-assemblies..valve means for controlling the supply of fluid from said fluid source to said cylinder-piston-assemblies, a reference member resting on said platen and movable in unison therewith, guiding means for guiding said reference member and maintaining the same in a position parallel to its starting position when said reference member moves with said platen, controlling means associated with said platen and said reference member and responsive to tiltin or bending movements of said platen for initiatsupply of pressure fluid to one of said cylinderpiston-assemblies to correct a tilting or bending movemuit of said platen, and adjustable means operable for predetermining the restriction of the flow of fluid to said respective cylinder-pistonassembly.

' 5. In combination in a press, a press platen, a

' reciprocable reference member resting on said prising a plurality of spaced fluid operable cylin- I platen and movable in unison therewith, means for maintaining said reference member parallel to the starting position of said reference member when the latter is in motion, contact means arranged at two spaced portions on said platen and adapted, in response to deflecting or tilting movements of said platen, to engage adjacent contact members on said reference member for closing a circuit, control means in said circuit responsive to the closure thereof for slowing down the movement of one platen end tending to run ahead of the opposite platen end, and means operable selectively for adjusting the respective position of said contact means relative to the respective contact members pertaining thereto.

6. In combination, a reciprocable element adapted when moving to deviate from its level position, means for reciprocating said element, a reference member separate from said means and arranged to move in unison with and to rest on said element, said reference member comprising a shaft having rigidly connected thereto a lurality of beams transverse to said shaft and at an angle with respect to each other, and guiding means for guiding said shaft to maintain said.

transverse beams parallel to their starting plane, when said reference member moves with said element, irrespective of tilting or bending movements of said element.

'7. .In combination in a press, a press head, a

when said reference members are moved with said platen, and a plurality of control means operable independentlyof each other and respectively associated with said reference members, each of said control members being responsive to tilting or bending movements of said platen for initiating a correcting movement of said platen to return the same to level position.

8. In combination in a press, a vertically movable press platen, a reference beam resting on said platen and movable therewith, horizontally spaced stationary guiding means for guiding said reference beam and to maintain the same parallel to its starting position when said beam moves together with said platen irrespective of tilting or bending movements of the latter. and control means adjacent the ends of said reference beam and responsive to a tilting or bending movement of said platen for initiating a correcting operation to return said platen to level position.

9. In combination, a reciprocable platenbeam or shear member, at least four spaced fluid operable cylinder-piston-assemblies arranged substantially in a row for reciprocating said platen beam or shear member, a fluid source for supplying pressure fluid to said cylinder-piston-assemblies, a. reference member resting on and movable in unison with said platen beam or shear member, guiding means for guiding said reference shear member, a plurality of controlling means corresponding in number to said cylinder-pistonassemblies and operable to effect a restriction of flow of fluid from said fluid source to said cylinder-piSton-assemblies, means responsive to a predetermined tilting or bending movement of said platen beam or shear member relative to said reference member for actuating the controlling means pertaining to one of the outermost cylin- 'der-piston-assemblies to restrict the flow of fluid. from said fluid source to said cylinder-pistonassemlflies, and means responsive to a larger predetermined tilting or bending movement of said platen beam or shear member for causing restriction of'the flow of fluid fromsaid'fluid source to the cylinder-piston-assembly adjacent the last mentioned cylinder-piston-assembiy.

10. Incombination in a press, a platen, fluid operable press piungers rigidly connected to said platen for operating the same, a reference meme ber, resting on said platen and being movable in unison therewith, means for maintaining said reference member in a posltionparallel to its starting position whilesaid reference member is moving with said platen, correcting means operable to vary the supply of pressure fluid to said plungem for correcting'a deflecting or tilting movement of said platen.- actuating means responsive platen respectively for initiating operation :or sa .to a ch nge in'. distance between reas ess mined points of. said reference memberandisa correcting means, and means associated withsaidc. actuating means and responsive to said change for imposing upon said actuating means a stroke larger than the change in distance between saidl two predetermined points. 1 1. In combination in a press, a platen, fluid, operable means for actuating said platen, a refer ence member separate from said fluid. operable means and resting on said platen so as to move in unison therewith, means for maintaining said reference member in a position parallel to its starting position when said reference member is moving with said platen. correcting means for correcting a deflecting or tilting movement of .said platen to restore the latter to its level position; and actuating means operable to actuate said correcting means, said actuating means comprising a lever system interconnecting said reference member and said platen and-'re'sponsiveto the relative movement of two "adjacent portions of said platen and said reference member respectively for causing a control element, associated with said correcting means, to move-over a distance greater than the stroke deflned by the relative movement of said adjacent portions.

nsvm E. BENCH. 

